After a few months of relatively low solar activity, the Sun might be about to spit out more solar flares.

Images of the Sun taken on December 4 show that it has five large sunspots and two long filaments of magnetism facing Earth.

“In the southeast limb, we see an extensive prominence, also in the southern hemisphere, but within the disk we can see the active region AR3153 that contains sunspots of a significant size, we also see a very extensive filament,” astrophotographer Eduardo Schaberger Poupeau from Argentina, told in reference to a picture he took of the Sun. “In the northern hemisphere, in addition to some interesting filaments, we see three active regions containing multiple sunspots.”

One other sunspot, named AR3157, also underwent a period of hyperactivity over the weekend before it turned toward Earth, with forecasts predicting it may send a solar flare or coronal mass ejection our way in the coming days.

Sunspots are areas of the Sun’s surface where the magnetic field holds a higher level of energy as a result of twisted magnetic field lines. When these twisted field lines suddenly release their stored energy, this can result in solar flares and coronal mass ejections (CMEs).

Solar flares are ejections of electromagnetic radiation—mostly X-rays— from the Sun, while CMEs are comprised of millions of tonnes of solar plasma. When aimed at the Earth, these solar events can have numerous impacts on the planet, depending on how powerful they are.

An image of the Sun on December 5 taken from the NASA SDO probe. Active sunspots AR3153 and AR3157 are labelled. Courtesy of NASA/SDO and the AIA, EVE, and HMI science teams. © Courtesy of NASA/SDO and the AIA, EVE, and HMI science teams.

Solar flares are classified according to how bright they are in the soft X-ray part of the spectrum,” Gonzalo José Carracedo Carballal, an astrophysics researcher at the Instituto Nacional de Técnica in Madrid, Spain, told Newsweek.

“The weakest are the A-class flares, followed in intensity by the B-class, C-class, M-class (these are “moderate”) and the X class. Each class represents a 10 times increase in the X-ray flux with respect to the previous: an M-class flare is 10 times stronger than a C-class, and 100 times stronger than a B-class,” he said. “A number between 1 and 9 can be appended to the letter, to distinguish between relative intensities within the same class (in the case of X flares, the number can be greater than 9).”

X-class flares, the most powerful rating, can result in planet-wide radio blackouts and long-lasting radiation storms.

“The emissions of X-rays ionizes the lower ionosphere (the D-region, at altitudes close to 80-90 kms), which actually absorbs [high frequency] radio waves, thereby stopping them from continuing up to the higher ionosphere where they get bounced back towards the ground,” Brett Carter, an associate professor in space physics at RMIT University in Australia, told Newsweek

“This absorption effectively causes the ‘radio blackout’…because the signals don’t reach their intended target(s).”

While solar flare intensity is measured using X-ray flux, this is not the only band that the Sun transmits on during solar flares.

“Sometimes, solar flares cause strong emissions in radio bands (called ‘solar radio bursts’), which can impact various radio applications on the dayside; e.g., GPS,” Carter said. “These are commonly (although, not always) associated with X-class solar flares, reaching higher towards and including R5 on the NOAA scale.”

“The rare (less than one per 11-year cycle) R5 X20 flares are the nasty ones that have the potential to impact many radio comms across the Earth, but it’s worth remembering that these impacts will be restricted to the dayside; i.e., the side of the Earth that is facing the Sun at the time of the eruption,” Carter said.

We rely heavily on electromagnetic communication, meaning that an event that could wipe them all out would be catastrophic. However, the likelihood of a solar flare knocking out radio transmissions across the globe is very small.

“The damage that solar storms (CMEs, flares and so on) cause depends on their strength, direction, polarity, etc,” Rami Qahwaji, a visual computing professor at the University of Bradford, previously told Newsweek.

“A number of conditions need to be satisfied for the maximum damage to occur. It happened in the past (the Carrington Event 1859), but back then we didn’t have critical digital infrastructure, similar to what we have today,” Qahwaji said. “But an event similar to the Carrington event happening today could result in between $0.6 and $2.6 trillion in damages to the U.S. alone, according to NASA spaceflight.”

The Sun is expected to continue to get more active as it approaches its solar maximum. Our star follows 11-year cycles of activity, experiencing its highest levels of activity during the maximum. The last solar minimum occurred in 2019, meaning that the next maximum is due in 2025.